Synthetic amphoteric polymers are useful in various applications, often as protein substitutes. Sterling, U.S. Pat. No. 4,075,131, discloses a conditioning shampoo containing a zwitterionic polymer which may be prepared by direct polymerization of acidic and basic monomers, e.g., acrylic acid and a dialkylaminoalkyl methacrylate.
Matsudaira et al., U.S. Pat. No. 3,985,698, disclose an acrylic resin for paints prepared from ethylenically unsaturated monomers having tertiary amine groups, e.g., N,N-diethyl- and N,N-dimethylaminoethyl methacrylate; ethylenically unsaturated monomers having carboxyl groups, e.g., acrylic acid; and acrylate or methacrylate esters.
Samour, U.S. Pat. No. 3,790,533, discloses pressure sensitive adhesive polymers comprised of certain carboxylic acid vinyl monomers, e.g., acrylic acid; an aminoalkyl acrylate or methacrylate, e.g., dimethylaminoethyl methacrylate; and an alkyl acrylate. Anderson et al., U.S. Pat. No. 3,853,803, disclose similar amphoteric polymers which are useful for producing crosslinkable, electrodepositable films and a technique for direct polymerization of these monomers with minimal reaction between the amino and carboxyl groups.
Synthetic amphoteric polymers have been used in photographic silver halide emulsions. Hollister et al., U.S. Pat. No. 3,749,577, disclose such a use for polymers prepared by direct polymerization of monomers having a carboxyl functionality, e.g., acrylic acid, and monomers having a quaternary ammonium functionality. U.S. Pat. No. 3,813,251 discloses such a use for similar polymers having a tertiary ammonium functionality.
Flint et al., U.S. Pat. No. 4,293,635, disclose a photosensitive composition comprising an amphoteric polymer which is an interpolymer of alkyl acrylamides, methacrylamides, aminoalkyl acrylates or methacrylates; acids, including acrylic and methacrylic acids; and acrylate or methacrylate esters.
Klein, U.S. Pat. No. 3,950,398, discloses water-soluble acid addition salts of methacrylic acid and 2-mono-(lower)alkyl-aminoethyl methacrylate in a molar ratio of 1.5:1 to 1:1.5. The salts can be homopolymerized to prepare amphoteric polymers or copolymerized.
Miyazako et al., U.S. Pat. No. 3,957,492, disclose a photographic emulsion which contains an amphoteric copolymer having morpholinyl-substituted alkylacrylamide groups and carboxylic metal salt groups and which can be used as a partial or complete gelatin replacement.
Smith et al., U.S. Pat. No. 3,692,753, disclose a silver halide emulsion comprising amphoteric polymers of, e.g., N,N-dimethyl- and N,N-diethylaminoethyl methacrylate, acrylic acid, and acrylamides or acrylates having thioalkyl groups in the alkyl chain.
In U.K. Patent Specification 889,760 are disclosed light-sensitive emulsions comprising amphoteric polymers prepared by hydrolysis of polymers containing groups capable of producing acidic and basic groups on hydrolysis.
Azorlosa, U.S. Pat. No. 2,592,107, discloses that amphoteric polymers can be prepared by hydrolysis of polymers of amines containing a vinyl radical or an N-acyl derivative thereof and vinyl, vinylidene or vinylene compounds containing potential acid-forming groups, e.g., esters of acrylic acid.
Shachat et al., U.S. Pat. No. 3,689,470, disclose a method of preparing polymers which contain a betaine-type group by direct polymerization of a tertiary amine-containing monomer and acrylic acid or aqueous methyl acrylate.